<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
    * {
        margin: 0;
        padding: 0;
        outline: 0;
    }
    .clearfix:after{
        content: '';
        display: block;
        clear: both;
    }
    .green{
        background-color: green;
    }
    .orange{
        background-color: orange;
    }
    .w150{
        width: 150px;
        height: 150px;
    }
    main{
        height: 100px;
    }
    .grail{
        /* 圣杯式三栏布局  padding 把左右的侧边栏的位置让出来*/
        padding: 0 150px;
    }
    .left{
        float: left;
    }
    .right{
        float:right;
    }
    .grail main{
        float: left;
        width: 100%;
    }
    .grail .left{
        position: relative;
        left: -150px;
        margin-left: -100%;
    }
    .grail .right{
        float: left;
        margin-left: -150px;
        right: -150px;
        position: relative;
    }
    </style>
</head>
<body>
    <div class="layout">
        <h4>方法一:圣杯布局</h4>
        <section class="grail clearfix">
            <!-- 自适应 -->
            <main class="green">main</main>
            <aside class="w150 left orange">aside</aside>
            <aside class="w150 right orange">aside</aside>
        </section>
    </div>
</body>
</html>